1. Field of the Invention
The invention relates to a starch film and a method for manufacturing a starch foam.
2. Description of the Related Art
The Waste Electrical and Electronic Equipment (WEEE) Directive (European Community directive 2002/96/EC) and the Restriction of Hazardous Substance (RoHS) Directive (European Community directive 2002/95/EC) have been published by the European Union (EU) since 2003, and obliges EU member states to transpose its provisions into national law for setting collection, recycling and recovery targets for all types of electrical goods. As of Jul. 2006, the maximum weight for the substances of lead, mercury, cadmium, chromium (VI), polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE) are prohibited by the RoHS Directive. If an electronic equipment has these substances which exceed the limit, the electronic equipment will not be allowed into EU member states. Manufacturing products in consideration of environmental friendliness (or so-called “green products’) is a major subject for the manufacturing industry. For green products, all parts of a product must conform to the proper directives. As such, manufacturing techniques specifically geared toward green products have increased in demand due to environmental friendliness.
With conventional plastics seldom being hard to self-decompose, they cause environmental issues when discarded. Thus, degradable plastics have been imported, researched and manufactured in many countries. Recently, developed countries have increased research for eco-materials, such as environmentally friendly materials. Meanwhile, cheap materials, such as PVC and EPS, are the main packaging materials previously used. Since PVC contains chlorine, it causes an environment issue during its whole life cycle, such as during production, use, and when discarded. PVC is called a “poison plastic” by Greenpeace International, and is deemed not fit for environmental demands. Thus, PVC has been substituted by polyolefin. However, no suitable material has been developed, that would feasibly be a substitute for ESP. Thus, increased methods for manufacturing and modeling materials which can be popularly or specially applied should be developed to meet demands for lower costs, recycling capabilities and environmental friendliness.
For example, cellulose, starch and chitosan are natural materials which can be decomposed in nature. In particular, starch is one of the best biodegradable raw materials due to its good processability and biodegradability.
Starch is a hydrophilic polymer and the hydroxyl groups therein react with the hydrogen bond of water. Thus, plastics formed of pure starch are not suitable for an environment with moisture. To address this issue, one solution is to mix the starch with hydrophobic polymers to improve water resistance. However, the compositions have shortcomings as performing uniform mixing is difficult and combining of the starch and the hydrophobic polymers may be weak.
Therefore, a starch composition capable of addressing the above issues is desired.